JP2000158312A - Face surface polishing device for panel for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent vibration of a grinding wheel and deformation or bent of an end of a panel by sucking a space provided between a polishing tool and a polishing jig into vacuum, sucking the polishing tool from a backside, deforming the polishing tool to a shape closing to an outer surface shape of a face surface, and generating tension in the polishing tool. SOLUTION: When a space between a rotating polishing jig body 9 and a polishing tool 1 is sucked into vacuum, the polishing tool 1 is sucked to deform a bent surface closing to a face surface of a panel 17. At this time, a base substance 2 is intended to be extended, but a reinforcing cloth in the base substance 2 resist against it, and therefore a strong tension state is provided. A cushion material 8 operates to the backside of the base body 2 with a suitable elastic force. When a polishing cycle starts, cooling water is discharged from a conduit 16, and a rotary table 18 starts rotating to rotate the panel 17. Next, when a rotation shaft 13 rotates and simultaneously falls to press the polishing tool 1 to the panel 17, the polishing tool 1 immediately becomes familiar to the face surface of the panel 17 and abuts to it at a large area, and polishing starts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for polishing an outer surface of a face portion of a CRT panel, that is, a face surface.

[0002]

2. Description of the Related Art Conventionally, a face of a cathode ray tube panel (hereinafter referred to as a panel) is polished by a device which relatively moves while pressing an elastically supported polishing tool against the panel while supplying abrasive slurry. ing.

[0003] This polishing step usually comprises three steps of rough polishing, medium polishing and gloss polishing. In this case, garnet used in rough polishing, permis in medium polishing, and cerium oxide in polished polishing are often used as abrasives.
It is often used as a polishing tool because it has a structure in which many steel cylinders are embedded in hard rubber for rough polishing, a rubber plate or rubber cylinder with medium rubber hardness for medium polishing, and an artificial plate for gloss polishing. A disk or tube made of leather or felt.

[0004] In any of the steps, the polishing tool has a flexibility for adjusting to the panel. As means for bringing the polishing tool into close contact with the panel, a cushioning material is provided inside the polishing jig for transmitting the polishing action to the polishing tool while holding the polishing tool. FIG. 3 shows a typical example of the prior art in the rough polishing step.

[0005] As shown in the figure, a polishing jig including a cushion member 23 and a metal polishing jig main body 24 is provided on the back side of a polishing jig including a steel piece (iron piece) 21 and a rubber base 22. Is provided. The polishing tool can be rotated and moved up and down via a polishing jig body 24 attached to a rotating shaft 25.
The face of the panel 17 placed on the surface is polished by the iron piece 21 using a polishing slurry. In this case, the polishing tool has an appropriate flexibility so as to adapt to the panel 17.

Next, the reason why the polishing tool needs to be flexible will be described. The main purpose of polishing the face of a panel is to remove small holes and wrinkles on the surface generated during molding while minimizing the polishing allowance. On the other hand, the shape of the outer surface of the as-formed panel is not always made to accurately match the product design. This is because the dimensional accuracy of the inner surface of a CRT is more important, and the molding conditions are controlled by giving priority to the dimensions of the inner surface during molding, so that the accuracy of the outer surface is generally not high.

[0007] Under these circumstances, even if the designed face shape is a spherical surface or a flat surface, it is necessary to perform the polishing while adjusting the polishing tool to each panel and generally following the panel. If you use a highly rigid polishing tool that deviates from this principle, the polishing allowance cannot be minimized,
For example, if you try to cut the surface as designed as if it were a machine tool, you need to polish extra dimensional errors, resulting in multiple times of polishing cost, resulting in reduced efficiency and consumption of polishing tools. Increase is a problem.

However, the flexibility of the polishing tool employed in the prior art may have a negative effect on obtaining a high-quality polished surface. This is because the restoring force of the cushion material is also applied to the portion where the polishing tool protrudes from the end of the panel, so that the polishing tool is bent and adversely affects the state of contact with the panel. Since the polishing pressure is large, an adverse effect particularly appears in the rough polishing step.

FIG. 4 shows the state slightly exaggerated. As is clear from the figure, when the polishing jig main body 24 is lowered and the iron piece 21 is pressed against the panel 17, only the upper portion of the cushion 17 is compressed by receiving a reaction force from the panel 17. As a result, the base 22 is bent at the end of the panel 17.

When the base is bent, the corners of the iron piece 21 come into point contact with the R portion (the connecting portion between the face portion and the skirt portion extending substantially perpendicular to the face portion) at the end of the panel. In addition to being scratched, the iron piece is lifted up or inadequately contacted at a point slightly inside from the end of the panel, thereby impairing the uniformity of polishing.

The degree of bending becomes more pronounced as the cushion material 23 has a higher elasticity like a sponge, and as the polishing pressure applied via the polishing tool body 24 is higher. On the other hand, elasticity is an important factor for adhesion of the polishing tool to the panel surface, and polishing pressure is an important factor for polishing efficiency.

That is, the bending phenomenon of the polishing tool is extremely inconvenient for polishing the panel. If the bending phenomenon can be alleviated, it is difficult to damage the R portion of the panel end, and the polishing uniformity at the panel end can be reduced. Improved polishing can be realized. Further, a higher polishing pressure can be applied, and the polishing efficiency can be improved.

On the other hand, there has been a long-awaited practical application of a technique for polishing a panel surface with fixed abrasive grains. The main reason is that the polishing method using free abrasive grains has the following problems.

The first problem is the instability of the abrasive.
Abrasives must be mixed with water to form a slurry, and a large-scale system needs to be supplied to the polishing equipment in large quantities.In addition, since the abrasives are constantly crushed and consumed, the state of particle size distribution, concentration, etc., is constantly controlled. It is not easy to do. For example, if the amount of the abrasive is too small, the particle size distribution is biased toward the fine side and a defect due to insufficient polishing occurs, and if it is excessive, the surface roughness is biased toward the large side and cannot be removed in the next polishing step. Coarse. For this reason, quality instability and productivity have been constantly reduced.

The second problem is the mixing of foreign matter. The raw material of the abrasive is usually mined from natural deposits, but may contain hard foreign materials, and if cracks occur during polishing, glass powder is mixed into the slurry system. These are by no means rare, and can cause scratches on the product, adversely affecting quality and yield.

[0016] The third problem is waste. A large amount of atomized abrasive is generated as waste. Although it can be diverted to other industrial raw materials, the cost of taking over is increasing, and this is a major problem in reusing. Originally, it should be recycled as glass raw material, but if you try to do so, equipment costs such as drying equipment and energy costs will increase, and in order to satisfy the constraint that there is no problem even if it is mixed with glass raw material, An expensive abrasive such as alundum must be used instead of garnet, and the manufacturing cost must be increased.

As the simplest means for solving the above problem, a method in which the iron piece 21 of the polishing tool is replaced with a pellet type diamond grindstone in the conventional polishing apparatus shown in FIG.

However, according to this method, not only the glass is deeply damaged but also the life of the grindstone cannot be obtained. The original life refers to the life when the whetstone is firmly fixed and used. The reason why the life of the grindstone is impaired is the occurrence of self-excited vibration. Self-excited vibration is a phenomenon that occurs when a solid supported by an elastic body is rubbed with another solid that moves at a constant relative speed. Therefore, the grinding stone having one end embedded in and protruding from an elastic body such as a rubber plate also has a condition for causing self-excited vibration.

Regarding this phenomenon, when the face of the panel is actually polished, the frictional force between the grindstone and the panel becomes a vibrating force at the start of polishing, and the grindstone starts vibrating violently. This mode of vibration is a complex one in which reciprocating vibration in the traveling direction of the grindstone and tilt vibration due to a falling moment generated by frictional force are combined.

In general, when polishing glass using a diamond grindstone, vibration is considered to be a great enemy. This is because the vibration causes repeated collision between the grinding wheel and the glass. When the impact is repeatedly applied to the abrasive grains embedded in the grindstone, the holding of the abrasive grains by the bond is gradually loosened, and the abrasive grains eventually fall out of the bond phase. This is referred to as abrasive grain shedding.

It is highly undesirable that shedding occurs before the abrasive grains wear out. This is because immediately after the abrasive grains fall off, the abrasive grains are sandwiched between the bond surface of the grindstone and the glass, and large abrasive grains that have not yet been worn cause deep scratches on the glass.

When the abrasive grains fall off, the bond phase is exposed at the polishing portion. Since this bond phase is made of a material which is extremely liable to be worn, it is worn by the polishing action, and as a result, loses the holding power of the abrasive grains and causes new dropping. The more frequent dropping occurs in this repetition, the greater the wear of the grindstone and the shorter the life of the grindstone. The vibration also causes a decrease in polishing efficiency. If vibrations occur in the grindstone during polishing, the efficiency of the grinding stone naturally decreases because the proportion of the polishing time in which the grindstone frequently separates from the glass and works effectively decreases.

For the above reasons, in general, fixed abrasive polishing is generally performed in such a manner that a grinding wheel mounting shaft having high rigidity and precision and a grinding wheel are rotated at a high speed, and the object to be polished is firmly held. This is because the grinding wheel does not vibrate and an excessive force is not applied to the diamond abrasive grains, so that the abrasive grains do not easily fall off, and problems such as generation of scratches and short life of the grinding stone can be solved. However, the fact that this method of using a highly rigid polishing tool is not suitable for panel polishing is
As described above.

Incidentally, in the case of polishing with an iron piece using an abrasive slurry, since there is no problem of abrasive particles falling off, vibration of the iron piece of the polishing tool does not cause any problem. That is, if the fixed abrasive polishing is performed by the conventional technique using a soft and flexible polishing tool, the above-mentioned principle of the fixed abrasive polishing is violated. Then, if the above-mentioned principle is to be adhered to, the polishing allowance must be increased many times, and the fixed abrasive polishing using the conventional technology faces a great contradiction.

Further, when fixed abrasive polishing is performed on a panel by the conventional technique, the bending phenomenon of a flexible polishing tool has a more remarkable effect than in the case of using an abrasive slurry. It was prone to problems. In other words, the abrasive grains embedded in the grindstone are usually harder than the abrasive material, and the content density is not higher than the abrasive material in the slurry, so if the grindstone makes point contact with the end of the panel, this part This is because the abrasive grains come into strong contact and cause much deeper flaws in the R portion.

[0026]

A first object of the present invention is to reduce the bending phenomenon of the polishing tool at the end of the panel when polishing the panel using a flexible polishing tool. An object of the present invention is to prevent the occurrence of defects due to point contact of a grindstone and to enable panel polishing with high polishing efficiency. A second object of the present invention is to enable fixed abrasive polishing of a panel, which has been difficult with the prior art.

[0027]

According to the present invention, there is provided a polishing tool having flexibility to be brought into contact with a face surface of a cathode ray tube panel, and a polishing jig for holding and rotating the polishing tool. In a polishing apparatus for polishing by pressing against the face surface while rotating a polishing tool, a space is provided between the polishing tool and the polishing jig, and the space is evacuated to form the polishing tool. Characterized in that the polishing tool is deformed into a shape close to the outer shape of the face surface by suctioning the polishing tool from the back side, and tension is generated in the polishing tool. Provide equipment.

[0028] The present invention also provides the above-described face surface polishing apparatus, wherein the polishing tool is substantially planar when the space is in a non-vacuum state. The present invention also provides the above-described face-surface polishing apparatus, wherein the polishing tool comprises a rubber base, a large number of grindstone supports embedded in the base, and a grindstone bonded to the grindstone support. Further, the present invention provides the above-mentioned face surface polishing apparatus in which a cushion material is provided in the space.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for grinding a face of a CRT panel according to the present invention is a polishing tool for applying a polishing action in contact with a panel, and a polishing tool for holding the polishing tool and transmitting a pressing force and a rotational force. A polishing jig is provided. A desired space is provided between the polishing tool and the polishing jig.

The most important feature of the present invention is that it has means for evacuating a space inside the polishing jig.
For this purpose, the polishing jig is provided with a vacuum supply mechanism for evacuating the space. As the vacuum supply mechanism, a general-purpose one can be used, which includes an operating valve and a device for adjusting the degree of vacuum.

According to the present invention, the polishing tool is provided with a vacuum supply mechanism as described above, and the polishing tool is sucked from the back side at the time of polishing, so that the polishing tool is adjusted to the curvature of the face of the panel, that is, the face is adjusted. It is characterized in that the polishing tool is curved and deformed so as to approach the outer shape of the surface, and that the polishing tool generates tension so as to be tensioned in the surface direction. The purpose of bending and deforming the polishing tool is to make the polishing tool contact the face surface as uniformly as possible at the start of polishing or during polishing. However, it is difficult to actually achieve this, and the curved shape may be very rough because the polishing tool is adapted to the face surface by its own elasticity and pressing force. The space portion of the polishing jig functions as a vacuum chamber when the polishing tool is bent and deformed, and also serves to secure a deformable space.

In the present invention, a preferable polishing tool for polishing fixed abrasives is composed of a rubber base, a large number of grindstone supports partially embedded in the base, and a grindstone bonded to the grindstone support. Become. The main purpose of making the substrate made of rubber is to obtain flexibility, and the rubber here is a general term for a material having flexibility, and is usually flexible and has a moderate elasticity. Various rubbers or synthetic resins are used. These can be used alone, but are often used in combination with a reinforcing material. As this reinforcing material, a reinforcing cloth is suitable from the viewpoint of easiness of processing, ease of compounding with the base material, and cost. However, in the case of a flat panel polishing tool having a high degree of flatness on the face surface, it is not necessary to curve the polishing tool, so a thin metal plate or metal mesh may be used. When actually reinforcing the base material, it is performed by embedding or laminating the base material.

In the present invention, the polishing tool attached to the polishing jig preferably has a substantially planar shape when the space is in a non-vacuum state. However, when the space is evacuated and the polishing tool is sucked from the back side, the polishing tool is bent and deformed in a concave shape with its periphery locked. At the same time, the polishing tool, which had been flat before, is curved and deformed, and thus tension is generated, and the polishing tool is placed in a tensioned state with respect to the panel.

It is more preferable to provide a cushion material in the space between the polishing tools. The reason is that when the polishing tool is pressed against the panel, the reaction force of the cushioning material acts on the back side of the polishing tool, which is effective to uniformly transmit the pressing force of the polishing tool to the polishing tool, This is because even when an excessive vacuum force acts when deformed by suction from the surface, unnecessary deformation of the polishing tool is suppressed, and the form can be stabilized. The cushioning material is preferably a breathable material.

Further, when performing fixed abrasive grinding according to the present invention, a large number of whetstones are firmly applied to a rubber substrate.
In addition, it is necessary to precisely join the surfaces used for polishing these grinding stones within the same surface. If the grindstone is not firmly fixed, the grindstone will be inclined with respect to the base during polishing, so that it will be unevenly contacted with the panel and uniform polishing cannot be obtained. Even when the surfaces of the grindstones are not the same, they do not evenly contact the panel.

The present invention can be applied to a polishing tool using free abrasive grains such as a polishing slurry. However, polishing using fixed abrasive grains such as a diamond grindstone, which has been difficult to put to practical use in panel polishing until now, is used. Especially suitable for tools.

[0037]

The operation in the case where the cathode ray tube panel is polished with a grindstone using the polishing apparatus of the present invention will be described. First, when the space in the polishing jig is evacuated, the polishing tool is sucked toward the polishing jig and deforms into a curved surface or spherical shape. At this time, if a cushion material is provided in the space of the polishing jig, the cushion material comes into contact with the cushion material and is stabilized in a state where it is compressed by a certain amount. At this time, the shape of the polishing tool becomes close to the shape of the outer surface of the panel face. At the same time, a strong tension is generated in the polishing tool with the deformation from the flat surface to the curved surface.

Next, the polishing tool is started by lowering the polishing tool and pressing the panel against the panel while rotating the polishing table and the base on which the panel is fixed, while allowing the coolant to flow out of the central hole of the polishing tool. At this time, since the polishing tool is curved in a concave shape, when pressed against the panel, the polishing tool easily conforms to the panel surface due to the flexibility of the base and the action of the cushioning material. The contact with the panel is maintained with a substantially predetermined contact pressure.

Further, the strong tension generated in the polishing tool causes a problem caused by holding the grindstone with a flexible substrate, that is, an effect of reducing the bending phenomenon of the polishing tool at the end of the panel and the vibration phenomenon of the grindstone. Having. The reason why this high tension is effective in solving these problems can be explained as follows.

First, the reduction of the bending phenomenon of the polishing tool at the panel end can be easily understood from the fact that local bending is corrected by applying tension in the plane of the base. Also,
Since this tension has a function of preventing wobble of the grindstone due to local bending deformation of the polishing tool even at a portion other than the end portion of the panel, it also has a remarkable effect in preventing vibration of the grindstone.

This effect increases as the tension increases, but it is better not to increase it further if a sufficient effect is achieved. Since tension has the effect of increasing the rigidity of the polishing tool,
If the height is excessively high, the adaptability of the polishing tool to the panel is impaired.

In this polishing apparatus, the tension is determined by the rigidity of the polishing tool with respect to the in-plane tension of the substrate and the degree of vacuum.
Further, since the radius of curvature (curvature) of the polishing tool is determined by these two factors, when the degree of vacuum is adjusted so that the radius of curvature becomes a target value, the rigidity of the base of the polishing tool is adjusted so that an optimal tension is generated. You only have to decide.

[0043]

Next, an embodiment in the case of fixed abrasive polishing will be described with reference to FIGS. FIG. 2 is a partially enlarged view of the polishing tool 1 of FIG. In the figure, 2 is a rubber base,
Reference numeral 3 denotes a grindstone support embedded in the base 2 in large numbers.
The base 2 is firmly joined by embedding one end in a rubber molding / vulcanization step. A grindstone 4 in which, for example, diamond abrasive grains are fixed in a bond phase and formed in a columnar shape is joined to the grindstone support 3. Reference numeral 5 denotes a reinforcing cloth embedded in the base 2, similarly to the grindstone support 3, which is firmly bonded to the base 2 during the rubber molding and vulcanization steps. A pipe 6 for fixing a rubber pipe 7 through which a cooling liquid passes is provided in the center of the polishing tool 1 as shown in FIG.

The polishing tool 1 is attached to a polishing jig main body 9 constituting a main part of the polishing tool by fixing an outer peripheral portion of the base 2 with a ring 11 and a bolt / nut 12. The polishing jig main body 9 has a bowl shape having a space therein, and when the polishing jig is attached, a predetermined space is formed between the polishing jig main body 9 and the polishing jig main body 9. A cushion material 8 is loaded in this space so that the pressing force applied from the polishing jig body 9 is uniformly transmitted to the polishing tool 1 (accurately, the base 2). The polishing jig body 9 is provided with an air flow hole 10 for evacuating the space where the cushion material 8 is loaded.

The polishing jig body 9 is mounted on a rotating shaft 13.
Since the rotating shaft 13 moves up and down through the support and is rotated by the drive belt 20, the polishing tool 1 rotates and moves up and down integrally with the polishing jig body 9. Inside the rotary shaft 13, an air flow hole 14 communicating with the air flow hole 10 of the polishing jig main body 9 is provided, and is connected to a vacuum source (not shown) via a fluid supply device 15. Thus, the space in which the cushion material is loaded can be evacuated.

A conduit 16 for supplying cooling water is provided at the center of the rotating shaft 13, and the cooling water supplied from the pipe 19 is supplied from the upper end of the rotating shaft 13 to the conduit 16.
And supplied from the rubber pipe 7 to the grindstone portion of the polishing tool. The panel 17 to be polished is fixed so as to be concentric with the turntable 18, and rotates around its own central axis during polishing. For the polishing operation between the panel and the polishing tool, a conventionally known method can be appropriately applied.

Next, the operation of the present apparatus will be described according to the actual polishing operation sequence. First, when starting operation of this device,
When the valve of the pipe leading to the vacuum source is opened, the space between the rotating polishing jig main body 9 and the polishing tool 1 is evacuated, and the polishing tool 1 is suctioned to a curved surface close to the face surface of the panel 17. Deform. At this time, the base 2 tends to be stretched, but the reinforcing cloth 5 inside the base 2 is in a strong tension state to resist it. The cushion material 8 acts on the back side of the base with an appropriate elasticity.

When the polishing cycle starts, cooling water is discharged from the conduit 16 and the turntable 18 starts rotating to rotate the panel. Next, when the rotating shaft 13 rotates and descends, and the polishing tool 1 is pressed against the panel, the polishing tool 1 immediately adjusts to the face surface of the panel and comes into contact with a large area, and polishing is started. When a predetermined polishing time has elapsed, the polishing jig rises and the polishing cycle ends.

[0049]

According to the present invention, before the polishing is started, the polishing tool 1 is deformed to a shape close to the outer surface shape of the panel by a vacuum force in advance. Since the material 8 is easily adapted to the work, the contact between the grinding stone 4 and the panel 17 is maintained at a substantially predetermined contact pressure. Thereby, the panel can be uniformly and efficiently polished.

Further, since a strong tension is generated in the base 2, the bending phenomenon of the polishing tool 1 at the end of the panel 17 is alleviated, and the phenomenon of damaging the R portion of the face surface is prevented. Further, it is possible to prevent a phenomenon in which the grindstone or the iron piece or the like floats or contacts insufficiently at a position slightly inside from the end of the panel, thereby impairing the uniformity of polishing. At the same time, since the holding of the grindstone 4 is firm, vibration is suppressed, and generation of scratches on the polished surface can be prevented.

When the base 2 is reinforced with a thin metal plate or metal mesh, the in-plane rigidity of the polishing tool 1 is increased. Therefore, the vacuum pressure on the back side is set higher and the curvature of the polishing tool 1 is adjusted to the face surface. A stronger tension can be generated to get closer. Thereby, the adaptability of the polishing tool 1 to the panel is slightly reduced, but the bending phenomenon at the end of the panel can be more completely prevented.

As described above, if fixed abrasive grinding is performed by the present apparatus, deep scratches and uneven polishing at the end of the panel are prevented because vibration of the grindstone and bending at the end of the panel do not occur. Can be prevented. In addition, since the polishing tool is well adapted to the panel, it is possible to prevent damage due to strong pressure generated on a part of the panel surface and to uniformly grind the panel.

Further, even when free abrasive polishing is performed by the apparatus of the present invention, since the bending phenomenon at the end of the panel is similarly eliminated, a higher polishing pressure can be applied and polishing at the end can be performed. Since the uniformity is improved, production efficiency and quality can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a polishing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing details of a polishing tool in FIG. 1;

FIG. 3 is an explanatory sectional view of a polishing apparatus in a rough polishing step according to a conventional technique.

FIG. 4 is an enlarged cross-sectional view showing a state of a grindstone at a panel end in a polishing apparatus according to a conventional technique.

[Explanation of symbols]

 1: Polishing tool 2: Base 3: Grinding stone support 4: Grinding stone 5: Reinforcement cloth 8: Cushion material 9: Polishing jig body 10: Air flow hole 13: Rotating shaft 14: Air flow hole 15: Fluid supply device 17: Panel 18: Rotary table

Claims (4)

[Claims] 1. A polishing tool having flexibility, which comes into contact with the face surface of a CRT panel, and a polishing jig for holding and rotating the polishing tool, wherein the polishing tool is rotated while the face is rotated. In a polishing device that presses against a surface to polish,
A space is provided between the polishing tool and the polishing jig, and the space is evacuated, and the polishing tool is sucked from the back side so that the polishing tool has an outer shape of the face surface. A face surface polishing apparatus for a cathode ray tube panel, characterized in that the polishing tool is deformed into a shape close to that of the above, and a tension is generated in the polishing tool. 2. The face surface polishing apparatus according to claim 1, wherein said polishing tool is substantially planar when said space is in a non-vacuum state. 3. The face surface polishing method according to claim 1, wherein said polishing tool comprises a rubber base, a plurality of whetstone supports embedded in said base, and a whetstone bonded to said whetstone support. apparatus. 4. The face surface polishing apparatus according to claim 1, wherein a cushion material is provided in the space.